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Thoughts on Survival Radio

Two-way radio should not be overlooked by preppers, this article is written to assist preppers in making radio equipment choices, and it is written on the premise of a post major event scenario in which all mains power utilities are permanently down.

Without mains power it is likely that there will also be no television, no telephone, no mobile phone, no internet, no radio repeaters etc. Radio will be the critical communications tool for monitoring the outside environment, communication with other survivors, and maybe for summoning help.

The author’s personal plan is to assemble a station that will allow discreet communication, locally, nationally and globally. The installation is required to be VERY covert so as to draw absolutely no attention to the station either pre or post event. The station is planned to be operational over a long time period (say 10 years), to be powered by simple power generation methods, and where possible be user serviceable using low(ish) tech solutions.

The manner of description of various issues has been very much simplified to aid comprehension of non specialist readers. This is particularly true in the section on Propagation and antennas. For anyone particularly interested in this subject there are many published articles that can be followed up.

1. Power supply considerations

Other than cats whisker crystal radios, all of the devices discussed in this article need electrical power. The most readily available power to survivors is likely to be 12v and solar rechargeable 1.2v dry cells. Additionally 12v to 5.2v USB car adaptors are now readily available at low cost. Recharging of these power supplies can be through mechanical generation of 12v and 5.2v by dynamo / alternators, or by solar cells. (for example, I have successfully run long term tests of solar recharging of AA cells using a bank of solar garden light heads. The recharged batteries have kept a very modest radio station running 24/7 for a whole year)

2. Basic specification of survival radios:
2.1 Low power consumption

Power will be a precious resource, which we will need to use carefully. Because of the power supply issues discussed above we should be looking for radios that have just enough power to make communication possible.

OK, so how shall we define low power? Well, radios with power output of 0.5w (watts) to 10w are completely capable of delivering reliable local and as well as global communications. (Radio amateurs refer to this as QRP power). It is logical to assume that low transmit power radios draw proportionately less power than high power transmitters. This is largely true, but not always so. (see section 8 Equipment Review)

Post-event, the number of privately held radio stations operating at high power will be extremely limited. This will have the effect of making low power radio stations even more effective as radio generated interference levels will also drop, allowing weak signals to be heard over greater distances.

Another aspect of using an appropriately small level of power is that it is more discreet, so attracting less unwanted attention from folk who may not have your best interests in mind when they hear your transmissions.

2.2 Robust

The operating conditions for survivalist radio equipment can be expected to be poor. Only robust equipment, or equipment who’s durability can be improved is likely to remain in service for long. As radios are sensitive (literally) electronic devices their biggest susceptibility is to getting wet. We need to purchase waterproof gear, or more economically, find ways to keep our gear in water-proof containers.

Again, power supply is going to be critical to long term viability of your equipment: The latest Lithium cell powered devices are going to be fine for a number of years operations (provided you can charge the batteries which are usually 7.2v) Best is to find devices that can be alternatively powered directly by a 12v supply, or by dry cells (AA, AAA etc)

2.3 Repairability

If long term usage is planned, it is a good idea to select equipment that is both repairable and within your competence to repair. Repairs to commercially manufactured equipment will be outside of the capability of most people. Transceivers with ultimate repairability are likely to be Amateur radio kits. However, a word of caution, by their very nature, such radios are inherently less reliable than most commercial units so require more running repairs.

2.4 Appropriate frequency ranges

It is important that the radios we acquire operate at frequencies that are either:-

  • in wide usage (to contact other survivors)
    • Broadcast FM receive bands for local Government Broadcasting
    • Broadcast AM receive bands for National Government Broadcasting
    • Broadcast LW receive bands for national and European Gov Broadcasting
    • Shortwave AM receive bands for worldwide Governmental Broadcasting
    • Shortwave Amateur Radio Bands
      • VHF / UHF FM Local Amateur Radio
      • High Frequency (HF) SSB and CW ( Single Side Band and Morse Code) Global amateur radio
  • or in restricted usage (for more covert group communications)

2.5 Availability:

We need to consider which users and equipment is most active and readily available pre-event as these will probably most prevalent after event as well. Standard radio receivers to pick up commercial and national broadcast stations: FM, MW (Medium Wave), LW (Long Wave) and SW (Short Wave) Available everywhere at very low prices. For local communications PMR446 family hand held walkie-talkie radios are the most prevalent radio transmitters in the UK today. Think about it: Probably most families with children will have several these radios in one form or another. All of these radios are simple to operate, somewhat child-proof and therefore robust, and they also conform to a very tight standard in terms of channel frequencies. They are not very repairable, but can be readily replaced.

Amateur Radio: Generally good quality and reliability, but complexity can be difficult to master without prior operating experience. Amateur radios can be a good choice, but remember most will be locked to frequencies allocated to amateur use. It is legal to own this type of radio, and indeed to use it as a receiver, but to transmit a license is required. (see Getting and Amateur radio License) Be warned that at the current time the amateur radio frequencies are policed and pirate stations are still tracked down and prosecuted in law.

CB Radio: Rather gone out of fashion in the UK, but radios are still available on e-bay at very low prices. Probably good only for pre-organised group local communications. Post event it is assumed that some dormant radios will be come back onto air, but there is no way of assessing what numbers are likely to be.

Marine VHF radios: Again, legal to own, but transmission not legal without a license. Restricted to marine band, which includes Coastguard, air-sea-rescue and Mountain search and rescue. Often bullet proof waterproof construction. If you live near to the sea, or better still a marina or even navigable rivers, there may be useful numbers of transceivers in place.

3. Understanding Propagation

Propagation is the technical term to describe how radio signals are radiated over various distances. Propagation is of great interest to us as it tells us what is possible, what is not possible with various pieces of equipment at various times.

3.1 A little science needs to be understood to make sense of propagation:

Radio waves are the lowest frequency section of the electro-magnetic radiation spectrum that includes infra-red, visible light, ultra-violet and x-Rays. Like visible light, radio waves generally travel in straight lines, and identically to light they travel at approximately 300,000km per second (186,000 miles per second in old money) in vacuum. From a point source (an antenna) radio waves will radiate in hemispherical pattern, much like half of a soap bubble. Using the same analogy, the bigger the bubble gets the weaker the signal that will be heard, a bit like the thickness of the wall of the bubble getting thinner and thinner as it expands. Like light radio waves will travel to infinity in a straight line. For example NASA’s communications with the voyager space probe used just a few watts of power to communicate half way across our solar system.

The concept of radio waves travelling is a straight line is important. Another way to look at it is that radio waves will only ever travel as far as Line-Of-Sight unless reflected, refracted or re-transmitted. Over the sea, line of sight is approximately 20 Km /12 miles. (see KD4SAI’s VHF/UHF Line of Sight Calculator) But this is far less than the distance we know radio waves can travel, how can radio waves overcome the ‘line of sight’ statement made earlier? Well the most simple way is the elevate the antenna: The higher it is the greater its line of sight. This is why mobile phone masts are located on hill tops, church towers and tall masts. At certain radio frequencies / wavelengths, radio waves are reflected and refracted by the upper layers of our atmosphere that get ionized by sunlight. These layers are like the layers of skin on an onion and are called the ionosphere. They exist at altitudes of between 85 and 250 Km. Radio waves hitting the layers of the ionosphere at critical angles and at critical radio frequencies / wavelengths, are reflected / refracted off and between the various ionized layers. In effect the ionosphere is a giant spherical mirror 100s of km above the earth that reflects certain radio frequencies (but not all) back to earth a great deal further than terrestrial line of sight.

The word critical has been used several times here. When light is separated by a prism into spectral colours the angle at which the incident light beam make with the glass prism is critical in determining if the light gets transmitted straight through the glass, reflected off its surface, or refracted within the prism. So it is with radio waves, other than at the critical angle the radio wave will pass straight through the ionosphere and out into space. Things are made more complicated as different radio frequencies have different critical angles, and the various reflective layers change in altitude and intensity throughout the solar day/night cycle. What is more some radio frequencies are not reflected by the Ionosphere at all. Frequencies in the VHF and UHF region are never reflected. This means that they are only suitable for line of sight communications. If you live on a mountain top this may mean 100Km or so, but generally it should be expected to get no more than 20km in ideal conditions. Ideal conditions get compromised by foliage buildings and other physical obstructions between transmitter and receiver.

3.2 Time of Day

At the lower High Frequency end of the Short Wave band, the frequencies of approx 2MHz to 30Mhz will all be reflected and refracted by the Ionosphere to a greater or lesser extent. Because of the variable critical angles and frequencies we can generally view Ionospheric propagation divided into usable daytime and night time frequencies. Broadly speaking, frequencies greater than 7Mhz will achieve longest propagation distances during daylight hours and frequencies below 7MHz will achieve longest propagation distances at night. The converse is also true after nightfall frequencies above 7MHz become progressively more line of sight, and after daybreak frequencies below 7MHz become progressively more line of sight (and the lower frequencies are affected by high levels of noise as well)

Ionospheric propagation frequently supports multiple reflection within the ionosphere without too much signal absorption. Under the right conditions trans global communications are possible at very low power. Communications between UK and Australia using 0.5W is possible. Here is an actual communication between USA and Indonesia using just 5w. These phenomena are possible only because of Ionospheric reflection.

3.3 Yearly and 11 year Cycle

The degree to which ionization takes place to the various layers of the ionosphere varies month to month and also within an 11 an (approx) 11 year cycle of solar sun-spot activity. Simply put, the higher the level of ionization the greater the efficiency of the Ionospheric reflector. This is particularly true at the 27/28/29MHz end of the spectrum which is almost worthless for long distance communication during low points in the 11 year cycle, but which becomes arguably the best long distance frequency at the high points of that cycle.

3.4 Dawn and Dusk

Dawn and dusk see some abnormal behavior of the Ionospheric reflector and sometimes offer conditions of enhanced long distance propagation. Monitoring at this time of day will often yield radio signals from unusual parts of the globe.

3.5 Skip Zone and NVIS

We know that radio signals travel by line of sight (say 20Km) unless reflected or refracted. So when a signal is successfully reflected from the ionosphere to a station say 1,500km away, what happens in the space between 20km and 1500Km? The answer is that nothing is heard in this zone. The radio signal beam is overhead at this time and cannot be detected at ground level. This is called the skip zone or Dead zone. This creates a dilemma, how do we communicate with stations within the skip zone, i.e. nationally, not internationally. Well the solution is to use an antenna technique developed for tactical military purposes. It is called NVIS (Near Vertical Incident Skywave). NVIS offers propagation to stations between the limit of line of sight and up to approx 1000Km.It is covered in the antenna section of this article (below)

3.6 Amateur Radio Repeaters

The purpose of Amateur repeaters is to extend the range of VHF and UHF communications by receiving signals on one frequency and re-transmitting them on another. Repeater masts located at the edge of a stations line of sight, and ideally in an elevated position will greatly extend the transmission range of the otherwise local only capability of this equipment. Indeed some repeaters are internet enabled and permit trans-global communications using simple hand held transmitters. In this article it is assumed that Amateur radio repeaters will be out of commission due to mains grid power failure, so will not be discussed further here. Again, for anyone wishing to find out more information on this aspect of Radio technology, much information is in the public domain on the www.

3.7 Propagation Conclusion (Applicable to transmission and reception)

  • Use frequencies below 7MHz for long range (DX) operating during hours of darkness.
  • Use frequencies above 7MHz for long range (DX) operating during daylight.
  • Use VHF and UHF frequencies for local communications day or night up to say 20Km.
  • For communications between 20Km and 1000Km NVIS antenna Techniques should be employed.

4. First seek to understand, then to be understood.

Recommendation is to firstly equip ourselves with a radio receives, so that we can listen for signs of activity in the surviving world. Listening to other people’s radio communications will give us good intelligence on what is going on around us without the need to leave our safe havens. It is very good practice to listen for an extended period in order to assess what is happening in the outside world. Gradually patterns of operating behavior will emerge that we will be able to predict. We must not be tempted into communication just for the sake of it. Listen first to see if predators are taking advantage of unwary stations in order to raid their locations. Our primary advantage will be our pre-preparedness, we should not squander it by giving away your location either directly or indirectly.

We should consider being able to monitor the following:

  • Broadcast bands: FM / AM / LW / SW
  • PMR446
  • Emergency services / Airband / Military (military comms will be scrambled)
  • Amateur Radio VHF / UHF (Local) and HF for world-wide transmissions

5. Transmitters and transceivers
5.1 Transmission Modes and efficiency

The method of encoding information into the transmitted signal is called the transmission Mode. The different modes available each have advantages and disadvantages from a quality: efficiency standpoint. By quality we mean the easiest to hear and understand, by efficiency we mean the greatest distance per Watt of transmitted power that the message remains intelligible.

FM Frequency Modulation: Highest quality but lowest efficiency. Excellent for VHF and UHF line of sight communications. Also used on UK legal CB frequencies to good effect. Very resistant to interference, and good intelligibility.
AM Amplitude Modulation: Similar characteristics to FM, but more prone to interference. Very inefficient power-wise. Largely unused these days by Amateurs, but still a major Broadcast format of course. Some illegal US import and vintage CB radios are still operative in UK on AM.
SSB Single Side Band: The most efficient voice transmission mode. Comes in two flavours Upper Side Band (USB) and Lower Side Band (LSB). Requires careful tuning of the receiver to render speech intelligible. Almost all long range voice communications are made in SSB mode.
Note: accepted operating convention is that for frequencies above 10MHz USB is used, below 10MHz LSB is used.
CW Continuous Wave ( Morse Code) Do not discount Morse code as outdated. It is by a very long way the most efficient transmission and reception mode available to us. 1/2watt power output (same as PMR446) but on HF bands regularly achieves trans global contacts on CW. In a survival communications scenario we will have time to study and learn the Morse code. Transmission can be very slow and repetitive to get messages across.
Tip: Morse code and to a lesser extent SSB can be resolved even on low cost AM receivers. Often the Morse code pulses can be heard as nulls in the background noise. Try placing a second receiver very close to and tuning it to a our active receiver and tuning it to a similar frequency. Often interference from the second receiver can be used to make the CW tone appear, likewise SSB can become more intelligible. A low cost BFO ( Beat Frequency Oscillator) kit is available from Ten Tec to perform this upgrade function more reliably.
Digital Modes A highly efficient digital mode called PSK 31 has been developed by amateurs. It involves the use of computers to generate automatic tone based keying of the transmitter. While very efficient transmission wise the fact that it requires a computer to drive it and interpret incoming signals disqualifies it as a low energy consumption communications method in this article.

5.2 Types of Transceiver;

5.2.1 PMR446
Not all PMR Radios are the same. USA import PMRs with extended range are being offered on e-bay at this time. They are illegal to use in the UK and are not compatible with the European PMR446 standard so cannot inter communicate with them. From a survivalist standpoint PMR446 is of interest primarily because of its high prevalence in the community. US PMR radios are only of interest if you plan semi-private group networks, but better solutions are available using the low cost Chinese hand helds described below and in section 8.
The ones we are interested in are of the PMR446 standard. These are all FM mode with 0.5w power output on 8 standard frequency channels through a built in, non removable antenna. Expect transmit range to be 1Km or less and you won’t be disappointed. In the open or in a good elevated location these radios will easily achieve the claimed 5Km range but such conditions are not the norm.
Ignore claims of hundreds of Channels this refers to so-called privacy codes (see below)
Features to look for are CTCSS and DCS tones and scanning, plug in headset sockets and the ability to operate with security codes off. (some early generation Motorolla radios do not have a no code facility)
Variable Squelch control is an asset. Squelch is a user tuneable noise threshold over which the receiver operates. It is designed so that your do not have to listen for signals within static as this is fatiguing, when a signal stronger than the background static is received, the receiver is opened up and the signal heard, otherwise the radio will be silent.
Radios that are sold with only AA or AAA dry cell / rechargeable cell capability are a better long term survivalist tool than those sold with bespoke power packs. Check to ensure that there will also run OK on rechargables and standard dry cells (different voltage therefore different amps to deliver the same output power.)
Radios with cases that can be unscrewed and dismantled are preferred, as, if you intend fitting an external antenna to improve reception you’ll need to get into that case somehow. But note that this will technically render the radio illegal under today’s legislation.

5.2.2 Hand Held Amateur VHF and UHF radios
1.0w to 5.0w capability FM radios with CTCSS and DCS capability
Range 3 to 10Km in normal condition, and up to full line of sight from open / elevated locations.
100+ memory channels, usually nameable and in fast retrieve blocks make operation fast and simple.
Some new low cost variants are now available out of Asia that off wide band transmit and receive capability such that single devices can now interact with Amateur VHF and UHF bands, Military Bands, PMR446 and Marine Band.
Marine band distress frequency as used by Coastguard, air sea rescue, mountain search and rescue.

5.2.2.1 Privacy codes and CTCSS / DCS tones
CTCSS and DCS tones appear on PMR446, CB and Amateur radios. They are all too often described a Privacy or secrecy tones, when in reality they are no such thing. These tones are discreet audio and Digital tones generated in the transmitter with are transmitted along with your voice signal. No encryption or secrecy coding is applied to the spoken message which can be listened to by any receiver tuned to the correct channel frequency.
The purpose of the tone is to allow suitably equipped receivers to ONLY HEAR signals on the same frequency to which they are tuned and also carrying the same discreetly injected tone (ie both transmitter and receiver must be set to the same frequency/channel AND also set to the same CTCSS or DCS tone, otherwise nothing will be heard). The intention of the technology is to enable concurrent multiple users of the same channel on PMR446 devices. It is only partially successful in this respect.
NOTE: During the Olympics there should be a lot of PMR446 activity in London with friends and families using them as a low cot way of keeping in touch. It will be interesting to monitor activity to see how well CTCSS and DCS systems work, also to hear what the system sound like in conditions of possible overload.
Some older PMR radios ( Mororolla for example) can only operate with CTCSS tones activated, the description of PMR446 requirements above notes that tone scanning is desirable as persons using such equipment will not be able to hear signals from you unless they carry the same discreet codes. Amateur radio has made most use of CTCSS coded as access codes to VHF and UHF repeaters (see Propagation section)
Monitoring with codes OFF allows you to hear everything in your vicinity.

5.2.3 Amateur HF radio equipment
Amateur HF radio equipment comes in all sorts of shapes and sizes. In the low power, portable category evaluated in this article the breadth of choice is somewhat reduced. There are both commercially constructed and kit type radios in this category.
Additionally there is ex British military equipment available. The author recognizes that this equipment may be ideal for survival communications, but has no experience of operating such equipment. Maybe someone with specialist knowledge can offer advice or write a specific article on this?
Primary separator between commercial machines and kits is transmission modes. Kits tend to be Morse code only, whereas commercial radios are voice and Morse code capable.

Commercial Manufacturers

Primary manufacturers are Yaesu, Icom, Kenwood and Alinco.

A lot of commercial transceivers are rated at 100w power output but gave variable power control, down to 5w. Read specifications carefully before rejecting a radio as too powerful. In the review at the end of this article I have only included radios capable of running at low power even if they are also capable of higher power output. Yaesu and Icom offer small form radios (car radio size) that potentially fit all survival radio requirements into a single box. They are broadband receivers that can tune the whole shortwave HF band, Air Band, Marine Band, VHF and UHF. They have sophisticated noise reduction systems that aid reception of weak signals and are capable of transmitting in AM/FM/SSB/ CW and digital modes. Among these, Yaesu’s FT817 is most recommended. Others from Yaesu are the FT857 and FT897 and from Icom the IC 706 and IC 7000.
Modern manufacturing processes are largely robotic, and components now used in construction of consumer electronics are super small. Modern machines are very reliable, but fixing them when something goes wrong is a complex affair.

Commercial transceivers are in four formats:

Hand Held Self contained ‘walkie-talkies’ for the VHF /UHF bands
Portable Self contained HF radio stations. Currently there are only three models in production. Yaesu’s FT817 (highly recommended) and the Albrecht AE 2990 10 meter hand-portable. Both offer Am /FM /SSB and CW modes. And a soon to be launched Elecraft KX3 which promises to be an excellent product for HF operating.
The Yaesu and Albrect both operate from rechargeable internal batteries as well as 12v external supplies.
Mobiles Small form factor radios for use in motor vehicles these are all 12v supplied, and available for both HF and VHF/UHF.
Desk top Large form factor radios designed to be used in fixed radio stations.

5.2.4 Kit Radios

HF radio kits are the prime interest here. VHF and UHF kits exist but they tend to cost very much more and have less features than their commercially manufactured equivalents.
Compared to commercial radios kits are far simpler and less refined, but are still capable of intercontinental communications.
HF kit radios are a fraction of the cost of commercial equipment, and have two big advantages in survivalist term:

  • They are extremely power efficient, and often will run happily on voltages from 7v to 15v.
  • They are user repairable long into the future provided you also have spare parts in your provisions.

Many of these kits are quite simple to construct. If you have built Airfix model in the past, the construction of many of these radios will be within your capability. Basic equipment you’ll need is solder, soldering iron, clippers, magnifying glass, and a test meter.
Although primarily Morse code only devices, there are a couple of SSB capable kits available too. Critically these are designed for the primary 7Mhz and 14Mhz frequency bands (see 6.7 below)
These radios can be constructed into very small containers, making them easy to store in waterproof boxes and thus strong contenders for inclusion in bug out provisions.
Consider this: With home brewed minimal solar cell battery power it has been possible to keep a receiving/transmitting station on line 24/7 for an entire 12 month period in southern England. There was no equipment failure whatsoever during the trial and it was considered probable that this setup could remain in service for several years. Communications across mainland Europe and also to a number of USA states were achieved during the trial period. Cost of the entire station was under £50.00.

Kit Radios in this category come in two power bands:

1/2Watt and below Lowest cost, Morse only. Require LOTS of time and Patience to achieve contacts. But they do work.
2w and above Higher cost, some SSB capable. Generally better receiver capability and slightly higher power make contacting distant stations easier and more reliable. 5w capable machines are the best of the bunch, some of which are claimed to considerably out perform some of the best commercial portable equipment.

6. Antennae

For the sake of our survival scenario, this section only focuses on easily installed discreet / stealth antenna systems that will provide reasonably efficient performance.

6.1 Some more theory

Antennas should wherever possible be tuned to the frequency being used. There is a direct relationship between the frequency (speed of vibration) and wave length. Imagine a long skipping ropes being shaken at a fixed frequency, a wave travels along the rope and then repeats itself, if the frequency at which the rope is shaken increases, the shape of the waves travelling in the rope also change, and will get shorter.
So it is with radio waves: the radio wave travels away from the frequency oscillator at the speed of light (300,000 Km per second) the distance the wave travels in one cycle is the Speed of light / second DIVIDED by the number of cycles per second.
Example

10 MHz 1 wavelength = 10,000,000 cycles / 300,000Km / Second
1 wavelength = 0.0333 Km
1 wavelength = 33.3 meters

6.2 Antenna Feed line and matching

All transmitters have to feed signal to antennas from where the signal is radiated.
Modern transmitter output circuits are designed to operate into a ‘load’ that would be presented by a tuned dipole antenna (see below) this is in the region of 50 Ohms. If the electrical load presented to the transmitter output circuit is incorrect the output circuit will be damaged, most probably its output transistor(s) will burn out and be destroyed.
If using coaxial cable to feed your antenna make sure that it is the correct type for your transmitter. Every modern transmitter that the author knows of is 50 Ohm output. For these 50 Ohm cable is required. Note that TV coaxial is 75 Ohm not 50 ohm so is not ideal ( but could be used in emergency) provided an ATU (Antenna Tuning Unit) and SWR (Standing Wave Meter) are employed to balance the load to the transmitter.
Output balance is monitored with a SWR meter. Perfect conditions exist for the transmitter’s output circuit when the SWR is at or close to 1:1 on the meter’s calibrated scale. Adjustment to the antenna load is made by adjustment to the length of the antenna element(s) and or by employing an ATU.
An ATU is a fairly simple device to manufacture at home and many designs are available on the WWW. Kits also exist form firms such as QRPkits.com (their BLT and SOTA tuners are ideal for low power stations and contain built in SWR Meters. Alternatively ATUs with or without SWR meters can be purchased off he shelf at UK Amateur Radio Suppliers, or of course e-bay.
There are automatic antenna tuners on the market that will automatically match loads to output circuits. These are excellent labour saving devices. They are, however electro-mechanical machines. They draw power to operate, and will eventually fail. The more robust solution is to purchase or construct a manual tuning unit. These will be user serviceable, but can also be expected to have far longer initial service life. The author still using a tuning unit that his father constructed more than 40 years ago, its never been serviced and continues to perform perfectly. Similar L Match units change hands on e-bay for less than £20.00
Note of caution: SWR should always be adjusted initially at low power and then again at the desired output power. This is to prevent initial mis-match from damaging output circuits.
The correct position for the SWR meter is as close as possible to the transmitter output, Ideally the ATU should be as near as possible to the antenna feed point, but this is frequently difficult achieve except in fixed frequency and end fed antenna installations.

6.3 Antenna Length

In an emergency, provided we have a suitable ATU, any length of any diameter cable can be used as an antenna and will function to a greater or lesser extent but correct length antennas are resonant to the radio frequencies they transmit and are far more efficient both in send and receive modes. A good a assessment of how much space is needed for an antenna is to allow enough length for ½ wavelength at the lowest operating frequency. This is the overall length you will require. For antennas such as the end fed ½ wavelenth described below, this length can be snaked all over the place if necessary.
½ Wavelengths calculate as follows:

3.5MHz ½ Wavelength = 40 meters / 120 ft
7.0 MHz ½ Wavelength = 20 meters / 60 ft
14.0 MHz ½ Wavelength = 10 meters / 30 ft
28.0 MHz ½ Wavelength = 5 meters / 1
145.0 MHz ½ Wavelength = 1 meters / 3 ft
433.0 MHz ½ Wavelength = 0.35 meters / 1 ft

NOTE: Simple wire antennas are very economic and easy to construct, provided you have enough wire. As part of prepping we should keep several hundred meters of fine gauge wire in our provisions, along with some means of measuring it.

6.4 Antenna types:

6.4.1 Dipole This is the classic horizontal radio antenna. It consists of two ¼ wavelength sections of wire, end to end with feed line attached at the centre.
Dipoles are highly efficient single frequency antennas which when properly tuned can be attached directly to the transmitter via coaxial cable
For VHF or UHF, Dipole antennas can be fairly effective when mounted high on a building. They can be polarized vertical or horizontal. (if expected traffic is likely to be from hand held radios, vertical polarization would be preferable. ( see coaxial cable notes)
A variation to the Dipole is the doublet which uses the same two sections of ¼ wavelength wire end to end, but this time fed from the transmitter via an antenna Tuning unit using balanced transmission line (parallel pair of wires) In this configuration the antenna will perform well on multiple bands higher that the fundamental ¼ wavelength to which it was cut.
6.4.2 End-Fed As the name implies this is a single length of wire fed from its end by the transmitter via an antenna matching unit. Experience has found that it is best to feed this antenna through and Unbalance to Unbalanced matching unit (Un Un) again, good quality units can be home constructed or purchased over the counter or from Web vendors
Cut to ½ wavelength at the lowest operating frequency it will perform well on higher frequencies as well.
This is my preferred stealth antenna. The wire can be very thin indeed, and because there is no feeder cable the antenna is almost invisible to the naked eye. It can be quite heavily contorted and will still function. In fact it is quite desirable to have both horizontal and vertical sections in the wire run of this antenna.
This type of antenna should not pass near to other electrical wiring and ideally away from metal window frames etc. If the radio operating position is not directly on the end of the ½ wavelength of wire, it can be successfully fed with balances transmission line (ideally ¼ wavelength in length) with the ground wire left unattached at the antenna end. (in this configuration it is called an end-fed-Zepp (named after the antenna type used on Zepplin balloons.)
6.4.3 Groundplane Antenna Vertical antennas are very strong performers for long distance communications, adequate for local line of site communications and very poor for NVIS activity.
This is a vertical antenna designed for single frequency use. It is constructed of a ¼ wavelength element suspended vertically, with three or more ¼ wavelength elements attached to the negative terminal at the feed point. These elements are called ground planes and are adjusted in angle and length to achieve a match to the transmitter circuits. This antenna is fed with co-axial cable. It should be mounted on a mast as high as possible for best results. Alternatively the antenna can be ground mounted with 8 to 16 tuned ground radials buried around it in a radiating pattern. Another alternative is to build a ½ wavelength of wire into a glass-fiber fishing rod and mount this vertically, in which case no ground planes are required (effectively this is a ½ wavelength vertical end fed wire.)
6.4.4 Yagi Beam antennas Yagi beam antennas as they are very obvious to the naked eye and do not fit the covert requirement of this article.
Your television receiver antenna is in all likelihood a Yagi. It consists of multiple antenna elements lined up one behind the other, This type of antenna concentrates energy in a single direction, it effectively focuses energy directionally both on transmit and receive.
It would be possible to convert a TV Yagi for use at UHF / PMR446.
Likewise an old FM radio reception Yagi could be converted to VHF usage.
If you have a fixed direction requirement for extra power this could be viable.
Amateurs use such beams dynamically, rotating them to fix onto distant weak signals. It is considered that such activity would draw too much attention to a survivor’s location, but the choice is yours.
Again, many articles are available on yagi construction on www.
6.5 Antenna Insulators Ends of antennas should be supported by insulating material. Commercially available insulators are excellent choice
In emergency cut lengths of PVC plastic perform almost as well. Small bore PVC waste pipe is a favorite.
6.6 Covert Installation Covert antennas can be erected in most places without drawing too much attention.
Best rule of thumb is to get as much wire as possible in the clear as high as possible.
If you have trees in your garden they can be used to support all manner of thin wire antennas.
Plastic guttering is also a good place to hide dipole antennas, not ideal, but serviceable.
Many radio amateurs have made contacts around the globe from dipole antennas supported within the lofts of their homes.
Vertical and end fed antennas can be run within PVC down pipes.
End fed antennas can be thrown from upper story windows over branches of nearby trees, thereby forming the desired horizontal and vertical elements.
NVIS: (Near vertical Incident Sky-wave) This is an antenna deployment technique that was developed for military use. By completely going against normal long distance (DX) antenna theory of mounting antennas as high as possible, low strung antennas were discovered to be able to bounce signals off of the near overhead ionosphere to stations that would normally be considered to be within the Skip /Dead zone. This technique delivers stations from 20 to many hundreds Km away. Simply erect an horizontal antenna a few inches or a few feet above the ground (against or on top of a fence for example). Remember to keep the antenna wire insulated from the fence and the ground otherwise it will become useless in wet / snowy conditions. This installation works best over highly conductive ground (ie waterlogged)

6.7 Suggested Primary Frequency antennas

  • 7Mhz band is particularly useful for long haul and NVIS operations. It is functional day and night all year round and is relatively unaffected by the 11 year sun-spot cycle.
    For this reason there is generally a lot of amateur radio activity in this band.
    Half wave antenna lengths of 20m should be manageable in all but the most confined gardens.
  • 14Mhz. is the Radio Amateur’s primary long haul band. It is somewhat affected by the 11 year sun spot cycle and is mostly only open during daylight hours. With ½ wavelength antennas of just 10m long, covert antennas are easily erected. Not suitable for NVIS operation.
    5w and 10w transmitter powers will reliably permit voice contacts over1000+ Km on this band.
  • 145 Mhz VHF dipole
  • 128MHz VHF dipole for emergency services rescue frequencies
  • 446Mhz (PMR) Groundplane or Dipole Mounted as high outside as possible outside of building will enable significantly broader range monitoring compared to fixed antenna from an indoor location. Shortest possible cable lengths between radio and antenna and highest grade cable very important, otherwise cheap long lengths of coax will attenuate all of the signal gain achieved by the external antenna. Consider being able to rig the entire radio on a retractable pole in an exterior position with extended headphone wires extended to the monitoring location.

7. Preparations
7.1 EMP

Electro Magnetic Pulse EMP has already been covered in some detail on this web site. From a radio perspective the worry is about damage to semiconductors and chips in our radio receivers and transmitters.
It has been mentioned that vintage valve gear is much less affected by EMP, and there are many articles written supporting this. The Author owns several Russian military tactical field radios that employ valve technology, but they are not considered part of primary survival radio needs for three simple reasons:

  • They are very large
  • They are very power hungry
  • They are very heavy. (for example my d.108 outputs 2.0w FM only and it weigh in at nearly 20Kg the same performance can be had from a low cost modern hand held that weighs just over 100g!!!)

For the author the solution is to build a suitable faraday cage type box to store the communication equipment within, along with any other electronic devices that are hoped to be preserved. There’s no way of knowing for sure that this will work though. For the time being the d.108 and its cousins are stored away just in case!!!

7.2 Amateur Radio Licensing

IMPORTANT: At the current time all radio transmissions in the UK are currently under the control of OFCOM. Other than PMR 446 license free family radio, and license free FM CB, no transmission may be made without a license issued by OFCOM.

However it is legal to own transmitting equipment, to listen to other peoples transmissions using that equipment. Preppers may legally own radio transmitters discussed in this article, provided they do not operate them outside of the rules laid out by OFCOM. In the scenario of a seriously major event, there is unlikely to be anyone policing radio usage, but in the meantime in order to get experience of setting up and using transmitting stations, a Radio Amateur license is required.
Obtaining an Amateur Radio Foundation License is recommended to anyone seriously prepping with radio communication in mind. The examination is very simple (most people take less than 20 min to complete it and there is a very high pass rate). Also there is no longer any requirement for competence at Morse Code. An element of the Foundation course is called Morse Appreciation, this is a very simple element that the author has never seen anyone fail. A Foundation license give legal access to the most important communications frequencies at transmitter power limited to 10 Watts. This is perfect for worldwide communications. Indeed as was argued earlier, restricted power is most appropriate training to preppers.
The easiest way to take the Foundation License will be through your local Amateur radio club. They will either be arranging training and examinations themselves, or will recommend you to the nearest club who is doing so. It is al a very friendly affair. You can expect to find a warm welcome to the radio hobby and most importantly a huge reservoir of knowledge to draw upon when you set up your first HF station.
I would recommend that you join the local radio club so that you can get the experience of operating with them on National Field Days (NFD) . These are days operating in open countryside, Usually clubs have fields in radio-advantaged locations that they have land-owner permission to use. Generally it is about self reliance in the open air. You’ll learn a lot of new radio skills, power supplies, ad hoc antenna rigging, and system weather proofing. At the same time will be able to dry-run your bug-out gear.

8. Equipment Review:
8.1 Receivers
(running from AA batteries)

Lowest Cost
Superdrug World-band receivers FM/AM/Shortwave £5.00 or less
Tesco World-band receivers FM/AM/Shortwave Approx £7.00

Medium Cost
Eton E5 AM, FM, LW, Shortwave and SSB/CW capable Approx £90.00
700 Nameable memories to store worldwide broadcast station frequencies
Some models ( aviator) also have air-band for listening to airport traffic.
SSB /CW capability allows monitoring of global amateur transmissions
Grundig G5 Rebranded Eton E5
Other companies making similar spec machines: AOR, Sony, Realistic, Lafayette, Anjan, Sangean, Tecsun, Degen,
The amateur radio equipment manufacturers also make very good receivers. Often transmitters include wide band receivers capable of monitoring both amateur and broadcast bands.
Second hand Amateur radio receivers offer interesting choice to the prepper. Units such as the Yaesu FRG7 are perfect shortwave receivers. They are entirely manual, with excellent long term reliability, and capacity to run from either Mains, 12v or dry cell. Typically they can be forund on e-bay for £70.00 or less. The drawbacks are that they are now mostly 30 years old, they are large format, and relatively complex to use. (Icom and Kenwoood make comparable machines.

8.2 Transceivers
8.2.1 Local Communications (up to 10km) hand Held FM transceivers operating on the VHF and UHF Bands

PMR radios: Select models like the Cobra, Motorolla and Binatone models that are powered by AAA or AA rechargeable batteries.
An interesting device that has come to market is the Midland base-camp. This is a PMR 446 radio built into a case that contains power generator, emergency flashlight FM and AM radio, and Marine band receiver. The author has discovered that this unit can be modded to deliver 40+ extra low power transmit / receive channels in the 70cm amateur radio spectrum. Such a mod would make breach the product type approval but might prove an interesting improvement on the unit’s capabilities.

Major Amateur Equipment ( Yaesu, Icom, Kenwood, Alinco)
Generally multi-power 1w / 2w/5w FM
Range: Line of sight.
Restricted to Amateur band transmissions
Excellent quality, some with great weather proofing
Some also have AM Shortwave receivers built in
Expect 100+ alpha-numeric nameable memories, scanning ultra-fast compared to low cost equipment below.
High speed full-band scanning capability with programmable scan frequency limits
Expect to pay £150 to £450 for brand new products
Generally these units have bespoke batteries and power supplies, converters for 12v operation are expensive extras.
Without exception these are robust, well engineered products. However cost, restriction to amateur bands and level of complexity may decide you against them. At extra cost some can be adapted to permit wide band transmit. If that cost is not a barrier, and with adaption to broadband, these radios are the ultimate choice.
New (Chinese )Amateur Radio Equipment Manufacturers
Amazing value Baofeng UV3R / Vero UV-X4
0.5w / 2w FM plus broadcast FM receiver and emergency light
Very low current drain, and long standby time.
Range: Line of sight
Diminutive size (Smallest in the market) and a clone of the far more sophisticated Yaesu VX-3R (£150+)
Mark II version usually comes with a single dual-band antenna and covert headset this is the recommended version.
Dual Band VHF and UHF

  • Receive and transmit capable in Amateur bands (VHF and UHF)
  • Receive and transmit capable in Marine Band (Coastguard Mountain & Air Sea Rescue)*
  • Receive and transmit capable on PMR446 frequencies*

*Even with an amateur radio license it is currently illegal to transmit on these frequencies
100 un-nameable memories, scanning slow and cumbersome compared to major amateur equipment.
SLOW speed full-band scanning capability with NO programmable scan frequency limits. This makes scanning tedious.
Expect to pay around £30.00 (e-bay) delivered
Run from inexpensive mobile phone rechargeable batteries that charge through USB ports. Alternate low cost AA/AAA battery carriers also available (£5.00 currently)
NKT and PUXING also offer excellent UHF radios of similar specification and slightly better performance / user interfaces and much better frequency scanning capability. Prices are similar, but they are UHF only so you do not get VHF amateur and Marine band capability.
Author has used small waterproof plastic boxes designed for mobile phones / cash/ documents to provide robust and waterproof protection of these radios. They have been carried on numerous mountain climbs in very adverse conditions over the last twelve months and the radios continue to perform perfectly.

Value Single band and dual band
Brands such as PUXING, Weierwei, Wouxun, Quansheng, TYT, FDC
1w/5w handheld FM VHF/UHF radios some with FM broadcast receive and emergency light
Range: Line of sight
Generally bespoke lithium Ion batteries, and inexpensive 12v connectors
100+ alpha-numeric nameable memories, with priority channel scan capability. Scanning slow and cumbersome compared to major commercial amateur equipment.
SLOW speed full-band scanning capability with programmable scan frequency limits
Expect to pay £60.00 for single band and £80 to £100 for Dual Band.
Wide band transmit capability similar to UV3R above, but offering higher transmit power.
These are robust semi-commercial products and units used by the author have provided many years reliable operation in extreme conditions.

8.2.2 Long Distance Communications HF transceivers
8.2.2.1 Commercial HF capable transceivers.

Yaesu
FT 817ND portable transceiver is the Swiss army knife of the radio world. It is small, light, and can operate in HF/VHF and UHF. It also has a wideband receiver built in that will pick up broadcast band through to Airband and FM broadcast radio. The radio can be modified to transmit outside of the designated Amateur radio bands. Output power is up to 5w Weakness of this radio is that it has relatively high current consumption ,and really needs to be used with an external power pack. Expect to pay £550 brand new and not much less second hand. ND model is the latest generation, non ND models sometimes had temperamental output transistors.
Similar radios in the Yaesu stable are the FT 857 (mobile / portable) and the FT 897(Mobile) both are competent radios capable of 5 or 10w power output or 100w maximum. Both have HF/VHF/UHF capability and broadband receivers supplemented with excellent digital receiver filters that will greatly assist in noisy operating conditions. Even more so than the FT817, both have standby high current consumption. Brand new cost in the region of £650 to £850.

Icom
IC 703+, now discontinued is an excellent dedicated low power radio if you can find one. Along with the FT817 this is one of the Amateur radio QRP specialists favorites. Designed for portable operation, with large easy to read display, digital signal processing, internal ATU, and variable power from 0.5w to 10w. Broadband receiver capability, but no internal battery, VHF, UHF Airband nor Marine band capability. Cost new was £500 second hand almost the same now! If you have a choice go for the later IC703 + model
Icom IC 718 (HF only) is a full featured FM AM SSB CW desk top radio that is simple to operate. It would suit someone new to radio. It has full HF band receive capability and will output from 5w to 100w. 12v power input. Brand new price in the region of £550
and IC706 and IC 7000 both are mobile type radios that cover HF VHF and UHF plus broadband receive. Both deliver 5w to 100w output. High(ish) 12v power consumption even on standby.
Elecraft’s new arrival the KX3 looks interesting and may well prove to be the successor to the Icom’s much admired but now discontinued IC 703. This is an HF transceiver delivering up to 10w. SSB CW and FM. It is designed for portable operation and as such can be predicted to draw minimal current on 12v.

Others to consider
SMC2020 0-20w HF SSB/CW/AM mobile radio ( discontinued)
Alinco DX-SR8T/E HF 5w to 100w SSB/CW/AM/FM
Kenwood TS 200 HF 5w to 100w SSB/CW/AM/FM

8.2.2.2 Kit Transceivers and receivers

Small Wonder labs
Rockmite 0.5w CW easy build, great reputation.
SW series 2.0w+ CW intermediate build. Serious wilderness radio.

QRP Kits
PFR3a 5 watt 3 band CW. Advanced build. Self contained station in a box RECOMMENDED.
BITX 20 10w SSB 14Mhz. Advance build. Recommended.
MMR-40 CW/SSB 7Mhz Advanced build.
BLT / Sota tuners Intern=mediate build. RECOMMENDED.

Ten Tec
R1056 Single band receiver ( build as 14mhz or 7 mhz) easy build. RECOMMENDED.
1320 / 1340 single band 3w Transceiver. Easy build. Recommended.
BFO to add CW/SSB to AM only Short wave receivers.

Elecraft
KX3 HF all mode QRP 10w portable transceiver Recommended.
K1 CW only 5w advance build. EXCELLENT performer.

HSC
Pixie II 0.2w CW any fixed frequency. Simple build, but really a last resort solution extreme patience needed to make any contact but its v. small, draws virtually no power and costs under £10.00.

You Kits
HB-1B 4 band CW 5w transceiver with broadband SSB and CW receive capability. Can be purchased as finished radio or as a kit from Waters and Stanton PLC

9.0 UK Ham Radio and component suppliers, and useful web sites

Martin Lynch
Nevada Radio
Waters and Stanton
Sandpiper antennas
Knights Radio
Maplin

OFCOM

10.0 Further reading and acknowledgements

A great resource for more in depth information on survival radio, and an inspiration for the writing of this article can be found on the AR15 for permission to use extracts of the Ham Radio 101 article and to include this link.

19 comments to Thoughts on Survival Radio

  • Northern Raider

    Gosh thats a bit short, could’nt you make it longer 🙂

  • Northern Raider

    More seriously this article is very informative, i would like to add this link for a review of the Intek 50 50 set, if you read the short article in full you will see why its so ideal for preppers

    http://www.transmission1.co.uk/2008/09/intek-mt-5050-professional-pmr-446-radio-review/

  • Lightspeed

    Sorry, I was in a bit of a rush! Will try harder next time.

  • Lightspeed

    Hi Northern Raider,

    I agree that the intek is a great PMR446 radio. Its primary advantage today over the Chinese products I have recommended is that it is entirely legal to use all of its features and no license is necessary. It is also a very robust and well and well made unit and can be expected to perform well in adverse conditions. For non licensed persons who are not happy with operating technically illegal equipment, teh Intek is arguably the best options available.

    On frequency agility though, the little UV3R Chinese handhelds is superior. Also its 4x more powerful in transmit but costs only half that of teh Intek: I purchased my ones as almost disposable toys that would let me retain a small degree of connectivity on the ham bands while being able to monitor PMR 446 as well. I have been hugely impressed with the performance of these radios, they are far beyong my expectation for the price paid. Receivers are very hot and transmit capability is right up there with Yaesu and Icom gear. Coupled with 1500mAh rechargable batteries at just GBP 5.00 each the cost benefit to me decisive. BUT and its a big but, these units can only be used today by licensed users, and the PMR446 compatibility can not be used legally under any circumstances. ( although Ofcom freely admit that it does not police PMR446 usage or intervene in interference problems)

    But I think we agree with the principal that PMR446 is going to be an important legacy format taht is likely to be a widely used tool by survivor communities.

  • Kenneth Eames

    Thank you for this article. I will need to study this, as I have no knowledge of radio at all. I will acquire some equipment and seek a lot more info. I will try to contact my nearest radio club. Kenneth Eames.

  • Lincolnoldie

    What a cracking read – absolutely stuffed full of information and really thought provoking for the genralist ie no info at all. Just shows who “we ” have at our “disposal”!

  • Northern Raider

    Hey Lightspeed please advise and clarify for me, cos I’m impressed with your expertise. You say the UV3R is 4 times more powerful than the MT 50 50, I think I’m losing the plot my friend cos I seem to think the UV3R is 2.2 watts, but if you snip the wire in the MT50 50 its 5 watts instead of 0.5 watts. Or am I barking up the wrong tree as usual ?

    • Lightspeed

      Hi Northern Raider,

      I didn’t realise the MT 50 could be converted. I thought it ewas a straight 500 mW PMR446 with additional LPD channels.

      That makes it very intersting. Un modded it is completely klegal, but if events mean you need more power it can be modded to 5w. That’s a good option to have.

      Thanks for correcting me.

      BR

      Lightspeed

      • Northern Raider

        Apparently if you cut the other two wires you get hundreds more channels on more bands as well ???

        • Lightspeed

          I’m guessing that this will extend the frequency range to all or some of the UHF Amateur band

          This will probably still not cover the VHF amateur bands not the Marine bands discussed before.

          But one thing that may be of interest. Dual band radios like teh UV3R tend to have compromised antennas, meaning that dual-band antennas sacrifice transmission efficiency in the interest of achieving broad bandwidth. Radios with restricted frequency range can have antennas tuned without compromise for maximum efficiency.

          Single band radios’ stock antennas can therefore be expected to perform beter than Dual Band antenna.

        • Lightspeed

          Northern Raider,
          Last night I read your excellent review of the Intek on the Forum section. (currently I cannot post on forum, but have requested access)

          The forum discussion of potential survivor group recognition codes is very interesting. Will keep comments attached to the appropriate Forum thread.

  • mike

    Dont forget for comms during or after a shtf event you’ll need radio comms that cam accomodate a microphone/earpiece/throat mike, as you dont want you comms audible and preferably one that can send a “noise” rather than speach to make contact if you find yourself in a compromising position and cant talk, yet need to send a warning.

  • Skean Dhude

    An excellent article. Just what we were looking for. I’ll certainly be looking at some kit when I get some spare cash.

  • Paul

    Good article, loads of info but I didn’t see the important frequencies listed i.e. The primary listening frequencies for emergency calls:-

    2182 khz Narine AM (On the hour and half hour FOR 3 MINS)
    Marine VHF AM CH 16 156.8 Mhz (any time)
    Aircraft AM 121.5 Mhz and 243Mhz Nato Aircraft (any time)
    Not forgetting CH 9 FM on the humble CB set or the common CH 19 FM genertal call channel. (any time)

  • Bug out Bag

    Brilliant article Lightspeed! I can give a big thumbs up to both the Baofeng UV -3R and the wind up Midland Base Camp PMR 446. Good info on covert antennas, much food for thought here. Thanks 🙂

  • Lightspeed

    Hiya B-O-B

    Thanks for the enthusiastic comment.

    I had a chance to play with a Midland basecamp at the weekend. It was an un-modded UK version with both PMR446 and LPD frequencies enabled. I really like the concept of a self powered ( hand generator) unit like this. Not sure about the price though….. it seems a bit steep.

    • Bug out Bag

      Hi Lightspeed,

      I agree it’s very pricey compared to the UV 3R,however for me the USP is most definitely its dynamo. It sounds like you have been playing with an identical model to mine which I bought online from a US supplier, I particularly wanted LPD. Incidentally, I have been quite busy in the last few days gathering bits and pieces ready to string up a couple of covert antennas and will be testing these on competition days 🙂

      Cheers,

      BoB

  • Lightspeed

    Hi BoB,

    I’d be interested to know exactly which LPD frequencies the Basecam is capable of. The one I played with briefly was transmitting, but as LPD Channe 1,2,3 etc. Does your unit have documentation that describes the frequency allocated to each channel? Certain LPD Channels are restricted to 100 milliwats and others to 10 milliwats……….either would make great uplinks to a remote transmitter 🙂

    Good luck with rigging the antenna wires. Be careful up there on high ladders. Probably easiest will be to rig up an end fed wire for NVIS on 7 Mhz. Wire should be around 20m/60ft long and suspended around 5 or 6ft above the ground…. it doesn’t have to be in a straight line so is ideal to tack onto a perimiter fence…..it’ll be pretty much invisible too. Diameter of the wire doesn’t matter, nore does it matter if its pvc coated or bare wire. Be sure to insulate it at all fixing points though.

    Good luck

  • ranger1

    Amateur radio is the way to go.
    Anything that saves walking is good communication.
    Lights from on top of a hill will also work. (big lights if possible)
    Via morse code.
    VHF..UHF also from a high point.

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